Toshiba GR200 Series Instruction Manual page 1727

addition to the current differential protection for the special case.
Therefore the condition shown in Table K-1 and Table K-2 should be replaced by that
in Table K-5 and Table K-6 respectively for "CASE 1".
Table K-5 CT Requirement defined by V
Td [ms]
35
50
75
100
150
Td [ms] Requirement 3
35 V ≧ I
k f_rev_max
50 V ≧ I
k f_rev_max
75 V ≧ I
k f_rev_max
100 V ≧ I
k f_rev_max
150 V ≧ I
k f_rev_max
V : Knee point voltage [V]
k
R : Secondary CT resistance [ohms]
ct
R : Actual secondary burden [ohms]
2
I : Maximum secondary fault current
fmax
I : Maximum secondary fault current at the zone 1 reach point
f_z1_max
I : Maximum secondary fault current for a close-up reverse fault
f_rev_max
I : Maximum secondary load current
Lmax
Max{I + I /2, I
Lmax fmin fmaxout
The larger of (I
I : Minimum fault current
fmin
I : Maximum out-flowing fault current for the special condition
fmaxout
Requirement 1
V ≧ I (R + R )×3
k fmax ct 2
V ≧ I (R + R )×3
k fmax ct 2
V ≧ I (R + R )×4
k fmax ct 2
V ≧ I (R + R )×4
k fmax ct 2
V ≧ I (R + R )×8
k fmax ct 2
(Rct+ R )×2 V
2
(Rct+ R )×3 V
2
(Rct+ R )×6 V
2
(Rct+ R )×6 V
2
(Rct+ R )×6 V
2
}:
+ I /2) and I
Lmax fmin
- 1704 -
(Special case)
k
Requirement 2
V ≧ I (R
k f_z1_max ct
V ≧ I (R
k f_z1_max ct
V ≧ I (R
k f_z1_max ct
V ≧ I (R
k f_z1_max ct
V ≧ I (R
k f_z1_max ct
Requirement 4
>
Max{I + I /2, I
k Lmax
fmin fmaxout
>
Max{I + I /2, I
k Lmax
fmin fmaxout
>
Max{I + I /2, I
k Lmax
fmin fmaxout
>
Max{I + I /2, I
k Lmax
fmin fmaxout
>
Max{I + I /2, I
k Lmax
fmin fmaxout
fmaxout
6F2S1914 (0.49)
+ R )×6
2
+ R )×7
2
+ R )×8
2
+ R )×8
2
+ R )×8
2
+ R )×14.4
} ×(R
ct 2
× (R + R )×20
}
ct 2
× (R + R )×28.8
}
ct 2
× (R + R )×36.8
}
ct 2
+ R )×50.4
×(R
}
ct 2
GRL200 (Soft 033 & 037)